The present invention generally relates to disposable wearing articles adapted to absorb and to contain bodily fluids such as sanitary napkin, urine pad or mother's milk pad.
A disposable diaper disclosed in Japanese Patent Application Publication No. 2001-95837A comprise a liquid-pervious topsheet lying on the side facing a wearer's body, a liquid-impervious backsheet lying on the side facing away from a wearer's body, an absorbent core interposed between these top- and backsheets and a pair of liquid-impervious leak-barrier sheets normally biased to rise on the core so as to define, as viewed in a longitudinal direction, front and rear waist regions, a crotch region extending between the waist regions, a pair of end flaps extending in a transverse direction outside longitudinally opposite ends of the core and a pair of side flaps extending in the longitudinal direction outside transversely opposite side edges of the core wherein the core is wrapped with tissue paper. In the known diaper, hot melt adhesives applied on the sheets and the tissue paper is used to join the top- and backsheets to each other, to join the leak-barrier sheets to the top- and backsheets, to join the tissue paper to the top- and backsheets and to join the core to the sheets and tissue paper.
In the diaper disclosed in the above-cited Publication, hot melt adhesives rather evenly applied on the sheets and the tissue paper forms a plurality of independent adhesive lines extending in the longitudinal direction, describing undulating curves. Of the adhesive lines, each pair of the adjacent adhesive lines are spaced apart from each other by a given distance in the transverse direction without intersecting each other while the individual adhesive lines intersect themselves in a few spots. Spread of adhesives on the sheets as well as on the tissue paper is in a range of 0.8 to 8 g/m2.
According to the disclosure of the above-cited Publication, a plurality of independent adhesive lines extending in the longitudinal direction describing undulated curves allow the sheets, the tissue paper and the core to be joined one to another with a substantially equal adhesive strength in the longitudinal and transverse directions and thereby to prevent the components from unintentionally peeling off one from another. Furthermore, the spread of the adhesives in a range of 0.8 to 8 g/m2 is effective to avoid an inconvenience that, even when a fibrous nonwoven fabric is used as a stock material for the topsheet, adhesives might clog fibrous interstices over a wide range and thereby to maintain a desired water-permeability of the topsheet.
In the case of the diaper disclosed in above-cited Publication, if the spread of adhesives on the sheets and the tissue paper is increased in order to reliably prevent the sheets, the tissue paper and the core from peeling off one from another, an excessive quantity of adhesives may seep into the fibrous interstices of the sheets and the tissue paper not only in the thickness direction but also in the planar direction. Consequently, cured adhesives may deteriorate a desired flexibility of the sheets. On the other hand, if the spread of adhesives on the sheets and the tissue paper is decreased in order to maintain the desired flexibility of the sheets, the adhesive strength required between the sheets, between the sheets and the tissue paper and between the core and the tissue paper may unacceptably reduced and the component may readily peel off one from another. For this diaper, adhesives rather evenly applied on the sheets and the tissue paper defines the adhesive lines, so the spread of adhesives can be adjusted merely by increasing or decreasing the spread of adhesives along the individual adhesive line as a whole. With a disadvantageous consequence, the adhesive strength required for the sheets, the tissue paper and the core is deteriorated and, if not, the flexibility of the sheets is deteriorated depending on the spread of adhesives. In this manner, it is difficult to ensure that the sheets, the tissue paper and the core are prevented from peeling off one from another and, at the same time, the flexibility of the sheets are maintained.